You only have to look at that video of the wreckage, look at what is left of that engine (just the core), look at the shredded aircraft skin, read the reports that there seems to be no major piece of wreckage and of course that no victims remains are likely to be found intact, and you realise that this airplane from just few thousand feet hit the sea with such force that it was akin to flying into a mountain face or a building. Assuming MH370's final act was a similar nose dive into the ocean, but from a much higher altitude, is it any wonder nothing has been found? The engine cores of MH370 and some landing gear would fall to the bottom to be indistinguishable among rocks and detritus while the rest of the aircraft shredded into a million tiny pieces would slowly sift itself over hundreds of square miles of the Indian Ocean as these pieces drifted in the current and slowly descended the four miles to the bottom. Very much a case of "there's nothing to see here folks, go home".
But this Lion Air accident happened in only thirty metres of water. So I guess most of the remains will be concentrated but they may be buried in a similar way to the Value Jet crash that buried itself deep in a swamp. Like the Lion Air crash, the Value Jet aircraft ( loss of control due to fire in their case) was airborne for just 10 minutes before it rolled over and head down at 860km/h impacting with the swamp near vertically. The aircraft was destroyed on impact, with no large pieces of the fuselage remaining, and like Lion Air there were little in the way of intact human remains. I guess why I'm comparing these two is to understand just how difficult it may be to find or extract the CVR from the ocean bed. Although, the pinger going off is a really good sign that maybe the CVR is still above the sea bottom. The FDR presumably was and I assume that they are both co- located in the tail?